In recent years, video signals have been made to have high bits and high resolution in accordance with improvements in the video image quality, and the amount of data transmitted by a digital interface also increases. A frequency increase is promoted to transmit a large amount of data, and signal transmission becomes difficult due to attenuation and the like in the transmission line under the influence of the increased frequency. In order to avoid this problem, there has been known a video signal compression technique and a multi-value signal transmission system to multiplex data in the voltage direction without frequency increase.
In addition, as a conventional technique to multiplex data in the voltage direction, a multi-value transmission system as described in PATENT LITERATURE 1 can be enumerated. Therefore, bit error is suppressed by changing the multi-value number in accordance with the error rate, and the error rate of the multi-value transmission can be reduced.